Dr. Eva Herzig
University of Bayreuth
Physikalisches Institut

Dr. Alexander Hexemer
Lawrence Berkeley National Laboratory
Advanced Light Source

The properties of functional coatings are strongly linked with the molecular morphology of the used materials. It is therefore desirable to gain as much control over the molecular arrangement as possible. While the chemical structure of the new materials plays an important role regarding film morphology, processing parameters have been recognised to be extremely important. Controlling these parameters however is challenging, especially for industrial manufacturing processes like printing, and the influence of the surrounding atmosphere is of utmost importance. The aim of the project is to join the expertise of the two groups to control and examine the influence of the processing parameters during deposition while using in-situ X-ray scattering experiments under grazing incidence geometry at a synchrotron facility. This experimental method reveals structural information with a high time resolution from several hundred to sub-nanometre length scales and is therefore used to systematically examine the morphology and linking it with the properties of organic thin films.

Final report:

A chamber encasing the slot die printer head and the sample allows the systematic control of the surrounding atmosphere during the printing process. Since the drying time has a significant influence on the structure formation in the printed organic thin film, the atmosphere chamber can be used to systematically control the drying time and therefore the structure formation. Apart from adjusting the substrate temperature and the common printing parameters like ink flow rate and deposition speed, the new chamber allows to also vary the atmosphere conditions. A strongly solvent enriched atmosphere therefore slows down the structure formation process, which can be tracked using in situ X-ray scattering and UV-Vis absorption measurements. Thanks to this project it was possible to gain fundamental results on structure formation in printed thin films of a multi-phase system. Further examinations are already ongoing.

Related Publications:
S. Pröller, et al., “Note: Setup for chemical atmospheric control during in situ grazing incidence X-ray scattering of printed thin films”, Review of Scientific Instruments 88, 066101 (2017)
S. Pröller, et al., “Following the morphology formation in situ in printed active layers for organic solar cells”, Advanced Energy Materials 6, 1501580